Looper-driving mechanism for sewing machines



May 26, 1925.

C. W. MUELLER LOOPER muvme MECHANISM FOR SEWING MACHINES Filed April 30.1925 2 Sheets-Sheet 1 Mania/1 C/za rkw W/Vzze/[m QMOQ M May 26, 1925.1,539,399

C. W. MUELLER LOOPER DRIVING MECHANISM FOR SEWING MACHINES File April30, 1923 2 Sheets-Sheet 2 May Patented May 26, 1925.

UNITED STATES PATENT oFFicE.

CHARLES W. MUELLER, OF ST. LOUIS, MISSOURI,,ASSIGNOR, BY MESN'EASSIGNMENTS, TO LEWIS INVISIBLE STITCH MACHINE 00., A CORPORATION OFMAINE.

LOOPER-DRIVING MECHANISM FOR SEWING MACHINES.

Application filed April 30, 1923. Serial No. 635,459.

To all 107mm it may concern:

' Be it known that I, CrrAnnEs W. MUELLER,

a citizen of the United States, residing at St. Louis, in the State ofMissouri, have I invented certain new and useful Improvements inLooper-Driving Mechanism for Sewing Machines, of which the following isa specification.

Sewing machine looper mechanism, particularly for blind-stitch sewingmachines, is known wherein a rock-shaft, driven from the main shaft, isemployed to impart four of the components of movement to a sixwaylooper, and an object of my invention is to provide, in thestitch-forming mechanism of a sewing machine, improved means for drivingsuch a rock-shaft controlled looper. An instance of such looperoperation including a rock-shaft is found in Patent No. 1,190,833,granted July 11, 1916 to James \Vhitelaw, and in the disclosure of anembodiment of my invention herein, for simplicity, I have illustratedvarious portions of the mechanism as substantially corresponding withthat illustrated in said lVhitelaw patent.

Among the particular objects of my invention are to provide aconstruction which is susceptible of operation at very high 30 speed,involving only light, simply-constructed parts mounted and cooperatingfor minimum vibration when very rapidly driven, and arranged for facileadjustment to vary the operative rang of looperanovement imparted fromthe rock-shaft. Other and further objects will become apparent to thoseskilled in the art from the following description, taken in conjunctionwith the accompanying drawings.

To these ends my invention consists in the features of construction andcombinations of parts hereinafter set forth and claimed,

In the drawings, Fig. 1 is a front elevation, with parts broken away, ofa chainstitch blind-stitcher equipped with loopermechanism embodying myinvention; Fig. 2 is a rear elevation of portions of the drivingmechanism, and Fig. 3 is a section on line 3-3 of Fig. 1, and Fig. 4 isa section vertically through the parts 38 etc. of Fig. 2.

The frame of the machine is shown as including an upper arm 10 and alower arm 10, the former having a suitable downward extension 10 tocarry a rigid presser foot 11 above which works the stitch-formingmechanism 12, while the lower arm 10" supports suitable work handlingand feeding mechanism 13 which need not be described in detail, butwhich will serve to present the work to the action of the needle 1 1through a suitable work-aperture in the presser foot 11. Drive shaft 15extends longitudinally through the upper arm and from it there is driventhe rotary cross-shaft or jack-shaft 16, extending through, the framefrom front to back, suitable gears 17 and 18 effecting constantlyoperative connection between the two shafts. A wrist pin 19 on thedriven gear 18 is connected by a link 20 with the reciprocable needlebar21 for which a rock-shaft 22, extending through the frame member 10serves as a pivotal support, the rocking of the shaft 22 having nooperative effect upon the needle bar. The front end of rock-shaft 22,however, has eccentric connection, as by crankpin 23, with the pivotblock 24: of a suitable six-way looper element 25, which may be ofconstruction as illustrated in said lVhitelaw patent. The rocking of theshaft 22 will impart four components of motion to the looper element 25,that is tosay, the components of rise and fall and of vibration in thedirection of needle travel. To receive the other components of movement,fore-aml-aft across the line of needle travel, the looper structure 25is pivoted as at 26 to the block 24 and above said block its stem isengaged by a vibratablo lever 27 which is pivoted between at its endsand at its upper end makes engagement by roller 28 with the groove of aface cam 29 mounted on main shaft 15, such arrangement substantiallycorresponding with that shown in said lVhitelaw patent.

In order to operate the rock shaft 22 very rapidly, as required by highspeed running of a machine, time the looper movements to procure asubstantial dwell at each end of the vibration of the looper in thedirection of needle travel, insure an advantage ous operation of thelooper element ditferentiating its speeds of linear travel in dif ferentportions of its excursion, and facilitate adjustment to vary its rangeof throw, I provide driving mechanism for rock shaft 22 substantially asshown in Fig. 2. Cross shaft 16 has a terminal enlargement 16 from whichprojects a crank pin 31 carrying a slide-block 32 that operates in theslideway 83 of a lever 3 L which is pivoted as at between its ends. Thelower end of this lever is longitudinally slotted as at 36 to receive inadjusted position the stem of a screw 38 which may be secured by nut 39in any desired adjustment in the slot and which forms a pivot stud forone end of link 40. This link has itsother end pivoted as at 41 to agear segment 42 of small radius which is pivoted as at 4L3 on avshaft-stub projecting from the frame directly above the shaft 22. Thegear segment meshes with a pinion 14 secured on the shaft 22.

Thus, constant rotation of shaft 16 from the main shaft 15 is converted,through the slide block and crank connections 3S31, into avariable-speed reciprocation of lever which is communicated onsubstantially horizontal line through link to the gear segment 42 whichin turn rocks the shaft 22 through its engagementof gear 44. Each of theparts thus provided is relatively small and light, so that reversals ofmovement may be, accomplished substantially withoutvibration of themachine and without undue wear on the bearings, facilitating very highspeed operations, and the vertical alignment of centers of shafts 16 and35 and of shafts 4-8 and 22, with the disposition of the transfer link40 to. work always substantially at right angles to such lines of centergives most effective movement to the leverage system involved, minimizesthe weight necessary for reasonable safety factor, and gives greatfreedom of design in the most favorable placement of the shafts in themachine frame, Also the link arrangement described and the adjustableconnection of one end thereof at variable distance from the center ofoscillation of the part to which it is connected permits quick andfacile adjustment of the working throw of the loope-r effected by theroeleshaf t 22.

lVhile I have herein described in detail the particular machine to whichmy invention is applied and a specific design of the mechanism which Ihave found satisfactory in operation, it will be understood thatchangesinay be made in the specific embodiment in matters of detailwithout de 'iarture from the spirit of my invention within the scope ofthe appended claims.

I claim:

1. A loopcr driving mechanism fora sewing machine comprising, incombination, a drive shaft, arock shaft, a. loopcr clement mounted toreceive four components of motion from said rock shaft, a cross shaftconstantly rotatable from said drive shaft, and means forc(nrunnnicating motion from said cross shaft to said rock shaftcomprising a pivoted lever operatively connected with, said cross shaftfor oscillation thereby, apinion .on the rock shaft, a gear segmentmeshing with said pinion, and a link connection between saidoscillatable lever and said gear segment.

2. In a sewing machine,the combination with a frame, a main shaftmounted therein, accessible at the frontof said frame, a looper. mountedat the front of said frame and having operative front connections withthe main shaft for imparting two components of movement to saidlooper,-a rock shaft connected with said looper for imparting fouradditional,components of movement thereto, andv connections between saidrock shaft and: said main shaft comprising a cross shaftextendingthrough the frame, gearing connecting said main shaft and,cross shaft, a crank on the rear end of said cross shaft, a slide blockthereon, lever pivoted to the rear, side of the frame and having aslideway engaged by said block, a pinionca-rried by therock shaft on therear side of the -fra1ne,a gear segment of small diametermounted on theframe above the: pinion, and agenerally horizontal link con nectionbetween said gear segment and the said lever;

-3.'A structure as set forth in claim '1, wherein the link is at one endconnected for adjustment radially to ard the axis of oscillation oftheparts to which it is connected.

, orianiins w. MUELLER.

